1. Field of the Invention
The present invention relates to a head suspension for a disk drive incorporated in an information processing apparatus such as a personal computer, and particularly, to a head suspension having a piezoelectric element that is attached with a nonconductive adhesive and deforms in response to a voltage applied thereto.
2. Description of Related Art
Small-sized, precision information devices are rapidly advancing, and for use with such devices, needs for micro-actuators capable of conducting positioning control for very small distances are increasing. Such micro-actuators are highly needed by, for example, optical systems for correcting focuses and inclination angles, ink jet printers for controlling ink heads, and magnetic disk drives for controlling magnetic heads.
The magnetic disk drives are strongly needed to increase their storage capacities. Increasing the storage capacity of a magnetic disk drive is generally achievable by increasing the storage capacity of each magnetic disk contained in the magnetic disk drive. The storage capacity or recording density of a magnetic disk will increase, without changing the diameter thereof, if the number of tracks per inch (TPI) on the magnetic disk is increased, i.e., if the width of a track is narrowed. For this, a magnetic head of a head suspension installed in the magnetic disk drive must conduct a precise positioning operation in a direction across the tracks, i.e., a sway direction. For realizing the precise positioning operation, an actuator capable of accurately moving and positioning the magnetic head in a very small area is needed.
To meet the need, the applicant of the present invention has proposed in Japanese Unexamined Patent Application Publication No. 2002-050140 a head suspension for a disk drive, including a base plate, a connection plate having a hinge thinner than the base plate, a load beam provided with a flexure, and a piezoelectric actuator having a pair of piezoelectric elements.
This related art employs a dual actuator system that involves, for a precise positioning purpose, a voice coil motor and the piezoelectric actuator having two piezoelectric elements made of, for example, PZT (lead zirconate titanate).
The piezoelectric actuator in the dual actuator system minutely moves a front end of the load beam in a widthwise direction (sway direction) of the head suspension. Compared with a single actuator system employing only the voice coil motor, the dual actuator system employing the voice coil motor and piezoelectric actuator is capable of more precisely positioning a magnetic head attached to a front end of the head suspension.
An important issue for the head suspension employing the dual actuator system is to secure originally required vibration and impact characteristics when attaching the piezoelectric elements to the head suspension.
One approach to address the issue is disclosed in Japanese Unexamined Patent Application Publications No. 2002-050140 and No. 2001-307442. According to these related arts, a base plate of a head suspension is provided with an opening for receiving a piezoelectric element and a pair of flexible links each having a U-shape and outwardly protruding from the opening. The piezoelectric element received in the opening is attached to the base plate with a nonconductive adhesive filled in a space between the piezoelectric element and the base plate.
According to the related arts, the pair of flexible links increases stiffness and sufficiently secures originally required vibration and impact characteristics.
The pair of outwardly protruding flexible links of the related arts, however, decreases a displacement stroke of the actuator, although the pair improves stiffness.